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M; sonnn, or PARIS, RANCE.

' METHOD OF PREsE'Rvme IRON AND STEEL'FROM RUST 0R OXlDATIQN.

Specification forming part of Letters Patent No. 5), dated December], 1533?.- v

To all whom it may concern; I

Be it known that I, M. SOREL, of the city of Paris, in the Kingdom of France, haveinvented or discovered a process, method, or methods by which various articles made of iron or steel may be effectually preserv'ed from oxidation .or rusting by the galvanic action produced by zinc; and I do hereby declare that the following is a full and exact description thereof. v

It is wellknown to-ohemists and to all persons versed in the physical sciences that'a galvanic-action is produced by the contact of two metals different in their natures, and that the most oxidizable of thesetwo metals so brought into contact becomes positively electrified,

while that which is least-oxidizable becomes 7 negatively electrified; and'also that when brought into this state the most oxidizable or positively electrified metal has a tendency to become oxidized and will abstract oxygen from compounds containing this agent, while the least oxidizablc of the two metals will be protected from oxidation although exposed to a gents which would oxidize it but for .the contact of the negative metals My process depends for its efliciency in protecting iron and steel from oxidizing or rusting upon the manner in which I apply this principle;

The process of covering articles of iron with tin is well known, and is exemplified most largely in'the manufacture of what is usually known under-the name of sheet-tin or tinplate, which consists of thin sheets of iron coated with tin. In this material there is necessarii y a galvanic action between the two metals;

' but it is to the disadvantage of that which it is proposed to protect-namely, the ironwhich, beingmore oxidizable than tin, becomes.

positively electrified, and has its tendency to rust increased, the protecting effect of the tin depending in this case entirely upon the per fectness with which the iron is coated by it,

as is clearly evinced by the rusting ofthe iron whenever any portion of this coating is, re-

moved and the iron is exposed to the action of 7 air and moisture. Ytere the galvanic action in favor of the iron, it would be protected notwithstanding the abrasion of the 'tin, as its protecting influence is not limited to the mere point of contact, but extends far beyond it.

In the scale-oi" the oxidability of the different.

metals, commencingwith those which are the most oxidablc, it has been found that zinc stands before iron, and it follows, therefore, that when these two metalsare brought into contact a protecting influence'will be exerted upon the iron by the zinc, and that the rusting of the former metal will'be thereby prevented."

4 It might be supposed'from the fact that zinc I is more oxidable than iron that this metal, if employed to protect iron, would itself soon become oxidized-or rusted, and would consequently leave the iron unprotected; and such reasoning would undoubtedly be just but for another fact, well known to chemists, -that' there are certain metals (of which zinc is one) which, after they have acquired a thin superficial coat of oxideyare thereby efi'ectually protected from the further absorption of oxygen underordina'ry exposure.

Having thus fully exemplified the principle upon the application of which my process is dependent for its efficacy, I will now proceedto give the necessary details and the various modes which I have devised for carrying the same into operation.

powderpvithoils or various materials, so as to .form a paint or varnish, with which the substancesto be protected are to be coveredin the,

ordinary manner of painting or varnishing; third,coverin g the articles to heprotected with the galvanic powder consisting of zinc finely comminuted; vfourth, wrapping the articles to be protected in what I denominate. galvanic -paper; fiftln'anoinling or covering the, ar'th cles with a galvanic paste, consisting of any suit able fatty matters-such as purified lardin which the galvanic powder has been freely mixed. '1

The first process-that of coating the a-rticles to be protected with metallic zine-4s to.

be eii'ectedmuch in the-same manner in which tinning is performed. that is to say, the articles to be coated must be rendered clean. and free from oxide by processes analogous to those followed in preparing them for ordinary tinning, such as immersing them in diluted sul- These modes which I have essayed are five in numhenand are as" follows: first, applying the zinc to the iron or steelin the manner in which tin is'applied in the process of tinning; second, applying a gab va'nic powder in the manner of paint, which consists in mixing the zinc, reduced to fine a -sno phuric or muriatic acid, scouring them, &c., which processes, being well known, need not be described. The zinc in like manner must be poured in proper crucibles or other convenient vessels adapted to the nature and size of of the metal may not adhere to them. They are then to be thrownin'to .cold water,rubbed with a sponge or brush, and dried as quickly as possible, as otherwise they may be injured by the appearance of dark spots, which it is desirable to avoid. When chains for cables or for other purposes are being withdrawn fronrthezinc they must be shaken" until sufficiently cooled to prevent the links from being soldered together by the melted metal. The coating of small chains requires careful management; but by the followinvg procedure it-is eflfected without difficulty: hile in the 'dilute acid they are to be moved about to expose all their parts equally to its action. They are then who dipped into muriatic acid and immediately dried in a rcverberatory furnace. The

melted zinc being ready and covered with salammonia'c, the chains are to be put into it and suffered to remain there about a minute. They are next slowly taken out by means of an iron skimmer or other convenientinstrument, which will allow as much of the zinc to drop'from them as can be got rid of in that way. .The links, however, will still'retain too much zinc, and will be soldered together. To correct this they are to be put into a reverberatory furnace, to be covered with charcoal,- and retained ate red heat for about a quarter of an hour, during'which time they are to be moved about by means of an iron poker. By this treatment the excess of zinc will be discharged. They are then to be drawn toward the mouth of the furnace, where they are kept in motion until the zinc is'solidified. When small nails and such like articles are to be coated the process should be performed in small crucibles, this being necessary to prevent the danger of spoiling a considerable portion of zinc, which results when iron has been kept in'it for a considerable length of time, as it is thus rendered unfit for the purpose of a protective coating. In all cases the purest zinc should be employed.

Wire may be coated by passing it through the melted zinc as it is wound off from one drum or reel'onto another. 7

When articles of wire have been coated with zinc it is sometimes desirable to cover this coating with one of 'tin, more especially when culinary vessels are the subjects of the operation.

It may also be resorted to when it is desired to give a bright and more handsome surface than the zinc affords. Such a coating of tin and itis to be effected in the ordinary way of firming, particular care being taken not to heat the tin too highly or to keep the articles in it so long as to remove any portion of the coating of zinc. The galvanic powder, consisting of zinc reduced to that state, may be obtained by various means. The following,

however, I have found to be the most cco-' nomical of any which I haye essayed. The zinc is put into a reverberatory furnace and brought nearly to a red hear, care being taken to prevent the access of a current of air. It. 7 .is then carefully skimmed. and covered with sal-ammonjac. Iron filings equal in weight to about one-tenth part of thefzincareto be moistened with muriatic acid and thrown on the fused zinc. The whole is to be covered withfinely-pulverized charcoal and the heat of the fused-metal raised to whiteness, and so retained for a quarter of an hour, agitating, it at intervals by means of an iron poker. The melted mass is then to be runoff into a brick or cast-iron reservoir, which is covered with. a

plate ofcast-iron to prevent the combustion of the zinc. Through an aperture in the cover a poker or stirrer is to be introduced .to agitate the alloy, which is to be done until it is cool, when it will be in fine powder. The galvanic paint is prepared by grinding this powder with the fluid which is to be employed to form it into a paint or varnish. Various fluids may be used for this purpose. I have sometimes employed the oil distilled from coal-tar.

Goal-tar itself answers well, with the addition of onethird'of spirits of turpentine, or of a sufiicient quantity to' bring it to a proper consistence. For purposes where the odor-of this mixture would be objectionable others may be substituted. Articles of polished steel or iron packe in this galvanic powder so asto be coveret thereby will be preserved from oxidation even should they become moistened from any accidental cause.

Galvanic paper may be prepared either by the mixing of the powder with the pulp in the manufacturing of the article or bytaking the ordinary wrapping-paper, coating it with any suitable adhesive substance, and sitting the galvanic powder over it. Polished or other articles wrapped in such paper will be eifecta ually protected from rust by the galvanic ac tlon. v

The preparation of the. galvanic paste has been sufficiently explained, and its operation in protecting the articles coated with'it will be readily understood, as it is analogous in this respect to those previously described.-

Having thus fully explained the principle upon which myprocess of protecting iron and steel from rusting or oxidating is dependent,

and having also givenv the various modes in which have contemplated the carrying the same i "to effect, I do hereby declare that what I claim as of my invention, and wish to secure by Letters Patent, is-- will not destroy the galvanic eii'ect of the zinc, i The employment of zinc invarious forms-as a protected, as herein set forth.

I do not claim to be the discoverer of the principle of the protection of metals from 01;-

- idation by galvanic action; nor do I claiin to be the first to have proposed the employment of zinc for, the preserving of iron therefrom,

masses of zinc having been applied, or it havillg been proposed to; apply it in masses to steam-engine boilers and probably to other or- 7 covering to the respective articles to be thereby ticles with this intention} but'from this my plan or. mode of procedure differs as obviously I Y as it surpasses it in efiicie'ney and in its applieability to numerous purposes in the arts where the application in masses-would be impossible .or altogether unavailable.

. SOREL.

Witnesses:

W. THOMPSON, THUS. P. JONES. 

